Snap action vane



April 12, 1955 .1. w. WELSH SNAP ACTION 'VANE 2 Sheets-Sheet 1 Filed Aug. 18. 1953 INVENTOR 1|||||l1l w||||| C f lilll I IEIIIM F F m ATTO NEY FIG.6

United States Patent Claims. (Cl. 200-422) N. J., assignor to Signal-Stat N. Y., a corporation of New This invention relates to a snap action device and, more particularly, to a novel thermostatically operated snap action switch having its main circuit controlling contacts normally open.

Thermostatically operated switches are frequently used as flashers for lamp circuits, such as the signal lamps of automotive vehicles. The operating mechanism is usually a thermomotive element, such as a bimetallic strip or an expansible high resistance wire. The thermomotive element is arranged to make and break the flasher contacts by alternately heating and cooling.

The heating of the thermomotive element is effected electrically, as by connecting this element in the operating circuit of the flasher. In the normally closed type of flasher, the thermomotive element is connected in series with the main contacts of the flasher so that it is heated while the flasher contacts are closed. When the thermomotive element is heated sufficiently to open the contacts, it thus breaks its own heating circuit and thereupon cools to re-close the flasher contacts.

In the normally open" type of flasher, a high resistance heating circuit for the thermomotive element is connected in shunt with the normally open flasher contacts, the current flow in such shunt circuit being insutfi cient to effectively energize the load controlled by the flasher, as the element is heated to a preset value, it closes the flasher contacts, thus forming a low resistance shunt around itself. The element thereupon cools to reopen the flasher contacts and repeat the cycle.

The present invention is directed to a novel and simplified normally open type of flasher having a high current carrying capacity and a snap action in opening and closing its contacts.

In my co-pending application, Serial No. 374,976, filed August 18, 1958, for Snap Action Device, I have shown and described a novel snap action vane which may be incorporated in a snap action switch. This vane is provided with an initial bend about a right line extending across the van by thinning or deforming the vane along this line in two or more spaced sections of the line, these sections being spaced at their inner ends from the center of the vane and also preferably spaced from the outer ends of the bent line. When such a vane is to be utilized in a snap action switch, such as a flasher, the vane is forcibly bent about another line, at an angle to the line of initial bending by applying force to the ends of such lines of initial bending. When such force is released, the vane snaps back to its initial bent position, the action closely resembling that of a toggle.

With a vane initially deformed in such a manner, the locked up stresses or forces have locii on elliptical lines or zones having radii centered on the center or mid-point of the vane located on the line of initial deformation midway between the inner ends of the spaced or discontinuous deformation. If the vane is held or fixed at a point on one of these locii, the remainder of the vane, during snapping thereof, pivots about such mounting point. The greatest effective force is exerted at the center of the locii but very substantial force is also exerted by portions of the vane located on the locii at the opposite side of the deformation line from the fixed mounting oint. P Such a vane may be effectively used in a thermostatic snap action switch by restraining the vane in the stressdeformed position by attaching a high resistance wire or strip at each of its ends to the vane at the ends of the line of initial bending. This high resistance wire or strip thus forcibly holds the vane in a distorted position bent about a line angularly related to the line of initial bending. When the high resistance wire has electric current passing therethrough, it heats and eXpands. During the expansion of the wire, a point is reached at which the tension exerted by the wire is over-balanced by the kinetic energy of the vane stored therein by bending the latter from its initial bent condition. At this point, the vane snaps back to its initially bent condition.

In the snapping action of the vane, the free portion of the vane extending from the vane mounting or pivot point has a relatively large amplitude movement relative to the pivot or mounting point. The present invention utilizes this characteristic of the vane to effect alternate closing and opening of a pair of load circuit controlling contacts.

More specifically, a relatively rigid mounting member or bracket is mechanically and electrically secured with the vane at a point on the surface of the vane opposite to the vane surface having the high resistance conductor extending thereacross. The vane mounting or pivot point is located laterally of the deformation line and preferably on one of the stress locii bands, with the bracket having a portion extending in spaced, and preferably parallel, relation to the vane across the deformation line.

On the same surface of the vane to which the mounting bracket is secured, the vane has a contact secured thereto. This contact is spaced laterally from the deformation line and on the opposite side thereof from the vane pivot point. By mounting such contact laterally of the deformation line, on the free portion of the vane, fully satisfactory contact pressure conditions are attained, for providing maximum make" pressures and minimum break pressures, particularly when the contact is mounted on one of the elliptical stress locii bands. The vane mounted contact is arranged to engage and disengage, during snapping of the vane, a cooperating contact mounted in insulated relation on the side of the extended bracket positioned nearest the vane.

When the vane is restrained in the stress-deformed position by the cold high resistance conductor, the free portion of the vane is bent away from the bracket extension, thus separating the two contacts. When the conductor is heated and expands a suflicient amount to allow the vane to snap to the restored position of the vane, the free portion of the vane snaps toward the bracket to snap the contacts closed.

A ballast resistance is connected to the high resistance conductor intermediate its ends and preferably at its mid point. To energize the flasher, one terminal of a source of potential is connected to a load which is, in turn, connected in shunt to the ballast resistance and the bracket mounted contact. The other source terminal is connected, through a switch, to the mounting bracket. When the switch is closed, current flows through the bracket into the vane and thence through both ends of the conductor to the ballast resistance and through the load. Due to the ballast resistance, the current through the load is at a minimum, non-effective value. The conductor beats and expands and the vane snaps to the restored condition. The snapping of the free portion of the vane toward the bracket snaps the vane contact into engagement with the bracket mounting contact. This closes a low resistance circuit through the load and shunting the high resistance conductor and its ballast resistance. The conducftYthereupon cools and contracts tosnap the vane to the stressdeformed condition, snapping the vane mounted contact away from the bracket mounted contact, and the cycle repeats.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

Fig. l is a perspective view of the snap action vane;

Fig. 2 is a reproduction of a photograph made, with polarized light, of the vane of Fig. 1 formed of transparent material, showing the elliptical stress concentration locii adjacent the vane center;

Fig. 3 is a perspective view of the mechanical components of the invention flasher;

Fig. 4 is a plan view of the flasher;

Fig. 5 is a transverse sectional view of the flasher on the line 55 of Fig. 3;

Fig. 6 is a graph of one operating cycle of the invention flasher; and

Figs. 7a through 7h graphically illustrate the vane movement during a cycle.

Referring to Fig. 1, which is substantially identical with Fig. 4 of my said co-pending application, Serial No. 374,976, a snap action vane 10 is illustrated which is identical with that shown and described therein. Vane 10 is preferably made of relatively thin spring metal, with consideration given to its spring factor, stiffness, temperature coefiicient, and the like, in accordance with the desired rate of operation of the snap action.

To provide an initial set to vane 10 and to give the same some depth so that it will resemble a beam in its action, the vane 10, which is shown as a substantially rectangular vane, is deformed or thinned along a diagonal interconnecting corners 11 and 12. This vane deformation is preferably effected by linearly embossing the vane along the line 1112 in two elongated spaced portions or bosses 15. It will be noted that the bosses have their inner ends disposed substantially equal distances from the center of vane 10 so that the center area of the vane is left unmarred. This greatly prolongs the life of vane 10 by removing the stress concentration from the center to a pair of points on bosses 15. If the deformation line 11-12 were continuous through the vane center area, the flattening of the vane at the center during repeated cycles would eventually cause fatigue of the vane at the center and reduce the amount of force required to snap the vane between the illustrated position and another deformed position.

Due to the bosses 15, 15, the sections 13 and 14 of the vane on either side of line 11-12 bend upwardly so that the vane assumes the form of a shallow vee (V) having its apex on line 1112. When vane bending forces are applied to the end of line 11-12, and the value of these forces equals or over-balances the inherent tendency of the vane to stay in its preset condition, the vane snaps into a new bent or deformed position, forming another shallow vee (V) along the other diagonal 1617. When the forces at points 11 and 12 are decreased to a point where they are over-balanced by the kinetic energy stored in vane 10 due to such distorting force, the vane snaps back to a position bent along the line 1112.

Photographs, taken with polarized light, of a transparent vane formed in this manner show lines of force in the unmarred center area of the vane which comprise elliptical bends 18 having radii centered on the vane center, as shown in Fig. 2. If the vane is secured or supported at a point on one of these elliptical stress locii, the stress points on the vane during application of bending force at corners 11 and 12 occur within the length of bosses 15. Thus, the stresses are removed from the center area and distributed between two points spaced from the center. This greatly prolongs the period before fatigue takes place in the stressed section of the vane.

Advantage is taken of this fact by supporting the vane by securing the latter, at a point of one of such elliptical lines of force, to a relatively rigid electrically conductive mounting member or bracket 20, as shown in Fig. 3. The point of attachment of the mounting member to the vane acts as a pivot point for the vane during its snap action, zlulid ilszpreferably spaced laterally of the initial bend line When the vane is used to form a snap action switch, the bending stresses may be conveniently applied to points 11 and 12 by means-of a high resistance wire or strip secured to these corners of the vane (Fig. 3). For this purpose, the points 11 and 12 are bent downwardly as illustrated in Fig. l, and the ends of wire or strip 30 are secured thereto at 31 and 32, while the vane is bent along the line 1617, so that the wire in its cold or contracted position holds the vane deformed into a vee (V) having its apex along lines 16 and 17. If wire 30 has electric current passed therethrough, it expands and, as the wire force is overbalanced by the restoring kinetic energy built up in vane 10, the vane snaps back to its initially bent condition along the line 1112.

During such snapping of vane 10, the free section thereof has relatively large amplitude of movement. An

arrangement for utilizing this action is shown in Figs. 3, 4 and 5, which illustrate the invention flasher. The point of attachment of bracket 20 to vane 10 is on the surface of the vane opposite to that having conductor 30 extending along. This mounting or vane pivot point is also laterally of diagonal 11-12, and preferably on a stress locii 18. The center section 21 of bracket 20 extends across line 1112 and, at a zone on the opposite side of line 1112 has a band 23 of insulation wrapped thereon. A conductive layer or band 24 is wrapped around band 23 and carries a contact 25 facing vane 10. A contact 35, mounted on the same surface of vane 10 as bracket 20 but on the opposite side of line 1112, cooperates with contact 25. Contact 35 is preferably mounted on one of the stress locii 18 to assure the maximum practical contact pressure conditions. In the illustrated stress-deformed position of vane 10, conductor 30 is contractgd and contact 35 has been snapped away from contact 5.

Conductor 30 has a ballast resistance 40 connected between its midpoint 36 and a grounded lamp load SL. Lamp SL is also connected, by conductor 41 to band 24. A grounded battery 42 is connected through a switch 43 to the outer end of bracket 20.

When switch 43 is closed, current flows from battery 42 through switch 43, bracket 20, vane 10, the ends of wire 30, ballast resistance 40 and lamp SL. Due to resistance 40, the current flow is insuflicient to light lamp SL. Conductor 30 heats and expands and, after a predetermined expansion of conductor 30, vane 10 snaps to its restored position, snapping contact 35 into engagement with contact 25. The current flow through the re sultant low resistance circuit is amply suflicient to light lamp SL. As resistance 40 and conductor 30 are now effectively shunted, conductor 30 cools and contracts. After a predetermined contraction of conductor 30, vane 10 snaps to the illustrated position to snap open contacts 25, 35. Lamp SL is extinguished and the cycle repeats.

Figs. 7a through 7h graphically depict the position of the vane parameters during the cycle represented in Fig. 6. As shown by the current line 45 in Fig. 6, substantially no current flows through contacts 25, 35 and lamp SL during the time that current is flowing through high resistance conductor 30 and ballast resistance 40. When conductor 30 expands sufficiently to allow vane 10 to snap to the restored position, contacts 25, 35 are snapped together and current then flows through lamp SL, with contacts 25, 35 shunting conductor 30 and ballast resistance 40. This is indicated by the elevated portion of current line 45 in Fig. 6.

In Figs. 7a through 7h, vane 10 and conductor 30 are indicated by the inverted vee (V) and straight solid lines respectively. The relations and values illustrated are relative only and not absolute. Lines a through e show the relative lengths of conductor 30, and line F shows the relative position of the vane mounting point which is, however, out of the plane illustrated in these Figs. Dashed line L is the relative equilibrium plane reached as vane 10 flattens, and changes as the vane snaps to the other position. Angle B is the angle vane 10 makes with a plane perpendicular to its mounting point, and is a measure of the stress in vane 10. The dotted line P is the relative plane of the contact 35, which is, however, not in the plane of the drawing.

Fig. 7a illustrates the parts with the vane in the stressdeformed condition, with conductor 30 cold and contacts 25, 35 separated. Conductor 30 is thus at its shortest length, touching lines b, and the vane center section is at its lowest point M. Angle B is thus large indicating great stress on the vane. Due to the large angle B, acting in the nature of a toggle joint, only a small force is needed to hold the vane in the illustrated condition. Conductor 30 is now starting to heat.

In Fig. 7b, conductor 30 has expanded to lines 0 and vane 10 has flattened somewhat, decreasing angle B and moving its center upward to point N. All these movements are relative to reference plane F. Due to the decrease in angle B, the pressure on conductor 30 is increased.

In Fig. 7c, conductor 30 has lengthened to lines a, angle B has increased, and the vane center is approachmg the flat condition so that its upward movement is slower. Contacts 25, 35 have approached each other slightly due to relative movement of the whole assembly toward plane F.

Fig. 7d illustrates the next position in which the described movements are accelerating. Conductor 30 has expanded to lines e, the vane center section is flat, and angle B has decreased further thus increasing the stress on conductor 30. This movement actually occurs in a very small time interval.

Fig. 7e illustrates the conditions after snapping of vane 10 to the restored condition. Conductor has moved to the equilibrium point or line. The downward movement of the vane corners 11, 12, relative to plane F, closes contacts 25, to shunt conductor 30. The latter thus starts to cool. In this position, conductor 30 has substantially the same length as in Fig. 7d, and the pressure on the conductor is somewhat less due to the reversal of the vane center. Angle B is quite small, but the vane apex angle is still smaller, contributing to a decrease in pressure on conductor 30, which latter can therefore contract.

As the conductor 30 contracts, it builds up pressure in vane 10. Angle B is increasing, the vane apex angle is decreasing, and conductor 30 has contracted to lines a and moved relatively downward a slight amount. The contact pressure is increasing due to the lever action of the parts.

In Fig. 7g, conductor 30 is still contracting but is beginning to move relatively upward due to the decreased rate of downward movement of the vane center as it approaches the fiat position. The pressure of conductor 30 on vane 10 has increased, accelerating the action. Angle B is increasing, indicating an increase in kinetic energy in the vane 10.

In Fig. 7h, conductor 30 has cooled and contracted to a greater extent. The contact pressure due to the lever arm is still substantial. The vane is about to snap to the position of Fig. 7a.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; means mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane; a second contact fixed relative to the vane mounting point and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and means including a high resistance electric circuit, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

2. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane; a second contact mounted on said member and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and means, including a high resistance electric circuit, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

3. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially degrees thereto; a first contact carried by the free portion of said vane, a second contact fixed relative to the vane mounting point and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and means including a high resistance electric circuit, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

4. A normally open thermostatic snap action electric switch comprising, in combination, a substantially fiat vane of resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter; a second contact mounted on said member and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and means, including a high resistance electric circuit, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

5. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and means, including a high resistance electric circuit, incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

6. A normally open thermostatic snap action electric switch comprising, in combination, a substantially fiat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress-deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and means, including a high resistance electric circuit, incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts,.when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

7. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; means mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial present position, the free portion of said vane will pivot said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress-deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially degrees thereto; a first contact carried by the free portion of said vane; a second contact fixed relative to the vane mounting point and selectively engageable with said first contact; said contacts being separated in the stressdeformed condition of said vane; and an electric energizing circuit including said element, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said energizing circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

8. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; means mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress-deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the'free portion of said vane; a second contact fixed relative to the vane mounting point and selectively en gageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and a high resistance electric energizing circuit including said element operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

9. A normally open thermostatic snap action electric switch comprising, in combination, a substantially fiat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress-deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane; a second contact fixed relative to the vane mounting point and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and an electric energizing circuit including said element, and incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said energizing circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

10. A normally open thermostatic snap action electric switch comprising, in combination, a substantially fiat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to efiect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistane electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over one surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress-deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane; a second contact fixed relative to the vane mounting point and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and a high resistance electric energizing circuit including said element, and incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

11. A normally open thermostatic snap action electric;

switch comprising, in combination, a substantially flat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and an electric energizing circuit including said element, and incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said energizing circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

12. A normally open thermostatic snap action electric switch comprising, in combination, an substantially fiat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and a high resistance electric energizing circuit including said element, and incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

13. A normally open thermostatic snap action electric switch comprising, in combination, a substantially fiat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and an electric energizing circuit including said element and a ballast resistance in series with said element operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said energizing circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

14. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation; an electrically conductive member mounting said vane at a point on one surface thereof spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting points; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and an electric energizing circuit including said element and a ballast resistance in series with said element at substantially the mid-point of said element, and incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

15. A normally open thermostatic snap action electric switch comprising, in combination, a substantially flat and rectangular vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross along a diagonal, said deformation being interrupted intermediate its ends at points substantially equidistant from the vane center to leave the central area of the vane free of preset deformation and with curvilinear stress concentration locii concentric with the vane center; an electrically conductive member mounting said vane at a point on one surface thereof on one of said locii spaced laterally from said deformation whereby, under bending stresses periodically applied to and released from points adjacent the outer ends of said deformation to effect snapping of the vane between a stress-deformed position and a restored initial preset position, the free portion of said vane will pivot about said mounting point; a heat expansible high resistance electrically conductive element secured at each end to said vanes at points adjacent the outer ends of said deformation and extending over the opposite surface of said vane in parallel relation to said deformation, said element, in the cooled and contracted condition, stressing said vane to a stress-deformed condition in which the vane is bent about a line bisecting said deformation at an angle of substantially 90 degrees thereto; a first contact carried by the free portion of said vane on said one surface of the latter on one of the stress locii, and on the other side of said deformation from the vane mounting point; a second contact mounted on said member in insulated relation thereto and selectively engageable with said first contact; said contacts being separated in the stress-deformed condition of said vane; and an electric energizing circuit in cluding said element and a ballast resistance in series with said element at substantially the mid-point of said element, and incorporating said vane and said member, operable to heat and expand said element to release its applied stress to provide for the vane snapping to its restored condition to engage said contacts; said contacts, when closed, shunting said high resistance circuit for cooling and contraction of said element to snap the vane to the stress-deformed position to open said contacts.

References Cited in the file of this patent UNITED STATES PATENTS 2,308,522 Leuthold Jan. 19, 1943 2,537,485 Sitzer et a1. Jan. 9, 1951 2,624,819 Spina et al. Jan. 6, 1953 

